In a wireless network having a star topology, a hub exchanges frames with one or more nodes. In the wireless devices representing the hub and nodes, a physical layer (PHY) is responsible for tasks such as activation and deactivation of the radio transceiver, clear channel assessment within the current channel, and data transmission and reception. The PHY also transforms a physical-layer service data unit (PSDU) into a physical-layer protocol data unit (PPDU) for transmission to other devices. The PSDU is typically pre-appended with a physical-layer preamble and a physical-layer header in order to create the PPDU. At the receiver, the physical-layer preamble and physical-layer header serve as aids in the demodulation, decoding and delivery of the PSDU.
The length of the preamble and the header (i.e., the number of bits or symbols in the preamble and/or the header) affect how much time and power is required to transmit or receive the PPDU. The length of the transmission times is proportional to the amount of power required from the wireless communication device, which is particularly important in battery-operated and portable devices. Additionally, because only one hub or node is transmitting at a time in a typical system, longer transmission times reduce opportunities for other devices to transmit during a superframe or beacon period. Accordingly, it is desirable to reduce the PPDU transmission time in order to reduce power consumption and increase device throughput.